Exhaled air is an effective way for our body to remove unwanted compounds. Each breath contains a variety of compounds produced as a byproduct of cellular metabolism, for example, carbon dioxide. The breath may also contain toxins that the body is trying to remove from its system. Additionally, as the breath leaves the lungs, an aerosol is formed comprising the contents of the bronchioalveolar lining.
Analysis of exhaled air can be used as a non-invasive method of diagnosis. Two examples of this that have found their way into common usage are the breathilizer test, which measures the percentage of alcohol present in the subject's exhaled air, which is indicative of the percentage of alcohol in the patient's blood, and the detection of acetone in the patient's breath giving the exhaled air a “fruity” smell, which indicative of diabetic ketoacidosis. Additionally, the non-gaseous portion of the breath may be analyzed to receive an indication of the composition of the aforementioned bronchioalveolar lining. This lining comprises antioxidants, proteins, epithelials, and a variety of other compounds that form an initial line of defense against inhaled oxidants (environmental pollutants) as well as airborne pathogens. By separating this condensate from the rest of the exhaled gases and performing an analysis of its content, the analysis may be used to gain a snapshot of the contents of the patient's bronchioalveolar lining.
The analysis of exhaled air can be used as a non-invasive diagnostic tool to identify what is in the patient's lungs. Commonly, this analysis will identify the presence of inflammation in the patient's lungs and the elevated presence of particular compounds can identify the source of this inflammation. Analysis of the exhaled air provides a system of early detection for ailments such as bacterial or viral infections as well as the early stages of lung cancer. Continued monitoring of a patient by collecting exhaled breath concentrate (EBC) samples and analyzing their content can provide a useful tool for detecting the progress of a disease and/or the treatment of the disease. This may be used for the treatment of chronic diseases such as allergies, cystic fibrosis (CF), and chronic obstructive pulmonary disease (COPD), but may also be used for monitoring the treatment of curable diseases such as bronchitis or pneumonia due to bacterial or viral infection.
An example of one such compound that may be monitored are isoprostanes, which are indicative of oxidative stress on the lungs. Increased levels of isoprostanes, particularly 8-isoprostane, have been shown to be indicative of asthma, CF, and COPD. Another example of a compound found in EBC that may be monitored for are vaso-active peptides, the presence of which are indicative of airway inflammation with the levels of these peptides being related to the severity of the inflammation. An example of a further type of analysis that may be performed on EBC is a UV-spectra of the EBC as the integral of the UV-spectra appears to be correlated to the surface area of the lung being used. However, these examples are not meant to be limiting as further analysis for compounds such as proteins, T-bars, hydrogen peroxide, DNA, and many others may be monitored to produce useful diagnostic information.
The collection of exhaled breath concentrate (EBC) presents a variety of challenges as the patient must generally go through several respiratory cycles in order to accumulate a sufficient amount of EBC for the required analysis. The collection of EBC currently requires the patient to be spontaneously breathing. Additionally, challenges exist in the condensing of the EBC out of the patient's breath while maintaining the EBC free from outside contaminants. Often a cooling mechanism is used to facilitate the condensing of the EBC from the exhaled breath, since cooling increases the efficiency of the condensating, thus requiring fewer respiratory cycles to obtain the desired sample amount.
Current EBC collectors are generally in the form of handheld devices, and these devices are cumbersome to use with a patient who is receiving mechanical ventilation. Beyond the fact that current handheld devices require the patient to be not only spontaneously breathing, but spontaneously breathing with the necessary force to over the resistance of the handheld device. The use of the handheld device requires temporarily taking the patient off of the ventilator, waiting the sufficient number of respiratory cycles while the handheld device obtains an EBC sample, then placing the patient back on ventilatory support. This task becomes nearly impossible if the patient is receiving mechanical ventilation through a more invasive type of patient connection, such as an endotrachial tube. The currently available EBC collection devices do not offer any integration ability with the breathing circuit of a mechanical ventilator.
Therefore, it is desirable in the field of respiratory care to provide an EBC sampler that may be used in conjunction with a patient receiving respiratory support via a mechanical ventilator without the patient being disconnected from the mechanical ventilator.